440 WILLIAM H. F. ADDISON 



apparently the polymorphous nuclei separate into small pieces. 

 These shrunken nuclear remnants stain more deeply than do 

 the original nuclei. The twenty-one-hour material shows spleno- 

 cytes containing some cells which still show red-stained granules, 

 and other cells in which the granules are no longer apparent. 



At the forty-eight-hour stage most of the inclusions have been 

 reduced to the condition of fine dark-staining granules, while 

 others (fig. 6) may still retain the original form of nucleus. Those 

 splenocytes (fig. 6) which contain cells which have been altered 

 but little, are usually larger than those in which the digestion 

 of the cells has advanced farther. Indeed, many of the spleno- 

 cytes are now but little larger than some found in the normal 

 spleen. They are, however, quite conspicuous, on account of 

 the intense staining of the nuclear remains within their cyto- 

 plasm. The digestion of the cells by the enzymes of the spleno- 

 cytes is evidently a process which requires considerable time. 

 At the twenty-one-hour stage no free myelocytes were found, 

 and relatively few polymorphonuclears, and it appears that the 

 splenocytes even at the sixteen-hour stage, were already well 

 filled. So it would seem that the cells ingested at sixteen to 

 twenty-one hours had not been completely digested by the 

 forty-eight-hour stage. 



These experiments indicate that the splenocytes can ingest 

 material from a very small size to cells 16 X 10 ju in dimension. 

 They also readily take up the ultramicroscopic aggregates of 

 trypan blue. So it is apparent that they have a very wide phago- 

 cytic capacity as regards size of object to be ingested. 



Viewing this in relation to their activity toward effete red 

 blood corpuscles of their own circulation, one must conclude 

 that they are capable of taking up either entire red blood-cells 

 or fragments of them. In a recent paper, Rous and Robertson 

 ('17) have found that phagocytosis of entire red cells is frequent 

 in normal dogs, rats, and guinea-pigs, slight in man, the rhesus 

 monkey, and many rabbits. This phenomenon is practically 

 absent in cats and in some dogs and some rabbits. In these latter 

 they find that fragmentation of the red cells occurs, and they 

 question how the fragments are disposed of. Judging by the 



